Pib as high viscosity lubricant base stock

ABSTRACT

Lubricant composition comprising a polyisobutene polymer having a number average molecular weight of 300-5000 g/mol and at least 60 mol % terminal double bonds based on the total number of double bonds in the polymer, and an ester component and/or an alkylated naphthalene compound having kinematic viscosity in the range of 2 to 15 mm 2 /s at 100° C.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national stage application (under 35 U.S.C. § 371) of PCT/EP2015/054390, filed Mar. 3, 2015, which is incorporated herein by reference in its entirety.

The present invention relates to the field of lubricants. The lubricant compositions contain a low viscosity ester and a viscosity improving component which is a highly reactive polyisobutene polymer having high degree of terminal double bonds. The lubricant compositions can be used in a variety of different formulations required in motor vehicles.

TECHNICAL BACKGROUND

Commercially available lubricant compositions are based on a multitude of different natural or synthetic components. The resulting properties of the various existing lubricant compositions are tailored to the specific technical requirements by the addition of further components and selected combinations thereof. In this way, lubricant compositions are obtained which can fulfill the complex requirements associated with the various special technical applications in the field of motor vehicles, automotive engines and other machinery.

Typically, lubricant compositions are needed that provide highest shear stability, improved low-temperature viscosity, minimum degree of evaporation loss, good fuel efficiency, acceptable seal compatibility and excellent wear protection.

One especially desired set of properties in high performance lubrication applications is an excellent low temperature profile indicated by favorable low temperature viscosity in combination with excellent dynamic behavior as indicated by high shear stability. Known lubricants which are able to fulfill such performance characteristics have been developed in the prior art by the addition of special thickening agents (viscosity index improving agents) to high quality base oils. Preferably, polyalphaolefin (PAO)-type base components have been modified with thickeners like polyisobutenes (PIB), oligomeric co-polymers (OCPs), polymethacrylates (PMAs) or even high viscosity esters (complex esters) for achieving the desired set of properties.

U.S. Pat. No. 5,451,630 describes the general dilemma when using thickening agents in lubricant compositions because the increase of viscosity is directly related to the molecular weight of the polymeric thickening agent while on the other hand the shear stability decreases due to the greater tendency of breakage under shear and high temperature conditions.

U.S. Pat. No. 5,451,630 further suggests oligomeric copolymers which are demonstrated to provide good shear stability to lubricant compositions.

In WO 2007/144079 A2, a larger number of lubricant compositions have been described including a variety of different thickening agents like PIBs, OCPs, PMAs and high viscosity esters which have been demonstrated to be useful as viscosity index improvers.

In addition, low viscosity esters like DIDA (diisodecyl adipate), DITA (diisotridecyl adipate) or TMTC (trimethyllolpropane caprylate) have also been added to lubricant compositions as solubilizers for polar additive types while further providing lubricity and seal compatibility.

On the other hand, despite the use of conventional polyisobutenes (PIB) as thickening agents in the preparation of lubricant compositions, so-called highly reactive polyisobutenes (HR-PIBs) comprising a high number of unsaturated terminal double bonds have only exceptionally tested as components in lubricant compositions although being commercially available under trade names like Glissopal® (from BASF). The reason may be that highly reactive polyisobutenes are considered prone to oxidation due to the presence of the additional terminal double bonds.

In US 2006/0287202 A1, it was demonstrated that highly reactive polyisobutenes can be used as alternative thickening agents in lubricant compositions by substituting a conventional polyisobutene thickener with a highly reactive polyisobutene component without significant deterioration of the resulting lubricant properties.

There is a continued need for lubricant compositions which are able to provide improved performance characteristics not found in the already existing ones.

One particular objective is to design improved lubricant compositions which are able to exhibit the desired rheological properties like shear stability and oxidation stability over a very broad temperature range including very low temperatures. Accordingly, it is desirable to develop lubricant compositions having very low pour point and low dynamic low temperature viscosity.

Surprisingly, it has been established by the present application that highly reactive polyisobutenes when combined with esters of rather low viscosity provide excellent lubricant compositions with very good performance characteristics in terms of shear stability and oxidation stability over a broad temperature range.

DESCRIPTION OF THE INVENTION

The present invention relates to a lubricant composition comprising

-   -   a) a polyisobutene polymer having a number average molecular         weight of 300-5000 g/mol, preferably 400-4000 g/mol, according         to DIN 55672 and at least 60 mol % terminal double bonds based         on the total number of double bonds in the polymer, and     -   b) an ester component having kinematic viscosity according to         DIN 51562-1 in the range of 2 to 15 mm²/s at 100° C. and/or an         alkylated naphthalene compound having kinematic viscosity         according to DIN 51562-1 in the range of 2 to 15 mm²/s at 100°         C.

In a preferred embodiment of the present invention, the ratio of the polyisobutene polymer having a number average molecular weight of 300-5000 g/mol, preferably 400-4000 g/mol, according to DIN 55672 and at least 60 mol % terminal double bonds to the ester component having kinematic viscosity according to DIN 51562-1 in the range of 2 to 10 mm²/s at 100° C. is from 1:12 to 12:1 and/or said lubricant composition contains 9.0 to 94.0 wt % of a polyisobutene polymer a) and 5 to 50 wt %, like 5 to 20 wt.-%, of the ester component b) based on the total amount of the lubricant composition.

In a preferred embodiment of the present invention, the lubricant composition further comprises 20 to 80 wt % of a base oil component.

In further preferred embodiments of the present invention, the base oil component of the lubricant composition comprises a PAO and/or a group II and/or Group III mineral oil, preferably a PAO 4, PAO 6 and/or PAO 8, wherein a PAO 6 is especially preferred base oil.

In another preferred lubricant composition according to the present invention, no further viscosity index improving component selected from the group consisting of an ethylene/propylene copolymer (OCP), a conventional polyisobutene polymer (PIB) having less than 60% terminal double bonds, a polyalkylmethacrylate (PMA) and/or a high-viscosity ester (complex ester) is present.

In a further preferred embodiment, the lubricant composition according to the present invention comprises an ester component which is selected from the list consisting of diisodecyladipate (DIDA), diisotridecyladipate (DITA) and trimethyloipropanolcaprylate (TMTC).

In another preferred embodiment, the lubricant composition further comprises an additive component selected from the list consisting of antioxidants, dispersants, foam inhibitors, demulsifiers, seal swelling agents, friction reducers, anti-wear agents, detergents, corrosion inhibitors, extreme pressure agents, metal deactivators, rust inhibitors, pour point depressants and mixtures thereof.

In another preferred embodiment, the additive component is present in an amount of 0.1 to 20 wt % of the total lubricant composition.

In another preferred embodiment, the lubricant composition according to the present invention has kinematic viscosity at −40° C. according to DIN 51562-1 of not higher than 110000 mm²/s, preferably not higher than 100000 mm²/s.

In another embodiment of the present invention, the lubricant compositions are used in light, medium and heavy duty engine oils, industrial engine oils, marine engine oils, automotive engine oils, crankshaft oils, compressor oils, refrigerator oils, hydrocarbon compressor oils, very low-temperature lubricating oils and fats, high temperature lubricating oils and fats, wire rope lubricants, textile machine oils, refrigerator oils, aviation and aerospace lubricants, aviation turbine oils, transmission oils, gas turbine oils, spindle oils, spin oils, traction fluids, transmission oils, plastic transmission oils, passenger car transmission oils, truck transmission oils, industrial transmission oils, industrial gear oils, insulating oils, instrument oils, brake fluids, transmission liquids, shock absorber oils, heat distribution medium oils, transformer oils, fats, chain oils, minimum quantity lubricants for metalworking operations, oil to the warm and cold working, oil for water-based metalworking liquids, oil for neat oil metalworking fluids, oil for semi-synthetic metalworking fluids, oil for synthetic metalworking fluids, drilling detergents for the soil exploration, hydraulic oils, in biodegradable lubricants or lubricating greases or waxes, chain saw oils, release agents, moulding fluids, gun, pistol and rifle lubricants or watch lubricants and food grade approved lubricants.

The lubricant compositions according to the present invention include the following components which are described below in more detail.

A highly reactive polyisobutene polymer is an essential component in the lubricant compositions according to the present invention. Such a highly reactive polyisobutene polymer is understood in its most generic manner in the context of the present invention as a polyisobutene polymer having at least 60 mol % terminal double bonds based on the total number of double bonds in the polymer.

Preferably, the highly reactive polyisobutene polymer as used in the lubricant compositions according to the present invention has a number average molecular weight of 400 to 2200 g/mol and has at least 60 mol % terminal double bonds, more preferably at least 75 mol % terminal double bonds and most preferably at least 85 mol % terminal double bonds based on the total number of double bonds in the polymer.

Highly reactive polyisobutene polymers as used in the lubricant compositions according to the present invention can be prepared following the established procedures including those of U.S. Pat. No. 5,962,604, U.S. Pat. No. 6,710,140, U.S. Pat. No. 6,683,138 or the like.

Highly reactive polyisobutene polymers are commercially available from several companies including the Glissopal® series from BASF.

The polyisobutene polymers are classified according to their kinematic viscosity (DIN 51562-1) which can be in the range from 30 to 1500 mm²/s [100° C.] and their number average molecular weight Mn (GPC) which ranges from 500 to 2500 g/mol. Preferred polyisobutene polymers as viscosity improving components in the lubricant compositions according to the present invention are those having viscosities in the range of from 30 to 45 mm²/s [100° C.] with a number average molecular weight Mn (GPC) of from 500 to 700 g/mol, viscosities of 160 to 220 mm²/s [100° C.] with a number average molecular weight Mn (GPC) of from 800 to 1200 g/mol, and viscosities of 1200 to 1600 mm²/s [100° C.] with a number average molecular weight Mn (GPC) of from 2000 to 2500 g/mol.

Exemplary polyisobutene polymers to be used in the lubricant compositions according to the present invention are Glissopal® V33, Glissopal® V 190 and Glissopal® V1500 from BASF SE.

The highly reactive polyisobutene polymer to be used in the lubricant compositions according to the present invention functions as a viscosity index improving component in the lubricant compositions and is present therein in an amount of 9 to 94 wt %, preferably 10 to 60 wt % or most preferably 12 to 35 wt % based on the total amount of the lubricant composition.

The lubricant composition according to the present invention comprising a highly reactive polyisobutene polymer can further comprise additional viscosity index improving agents. Viscosity index improving agents are thickener components that are able to increase the viscosity of a lubricant composition when added to it. Viscosity index improving agents typically include conventional polyisobutenes (PIBs) having no terminal double bonds, oligomeric copolymers (OCRs), high-viscosity (complex) esters, polymethacrylates (PMAs) or the like.

However, in a preferred embodiment of the present invention, these additional viscosity index improving agents are absent from the lubricant compositions according to the present invention, either individually or in combination.

In a preferred embodiment of the present invention, conventional polyisobutenes (PIBs) without terminal double bonds are absent from the lubricant compositions according to the present invention.

The term “conventional polyisobutenes” as used in the present application relates to polyisobutenes which have less than 60 mol % terminal double bonds, preferably less than 50 mol % terminal double bonds and most preferably less than 30 mol % terminal double bonds. Conventional polyisobutenes therefore differ in the latter aspect from the highly reactive polyisobutenes that have at least 60 mol % high degree of terminal double bonds. One preferred conventional polyisobutene is Lubrizol 8406®.

In another preferred embodiment of the present invention, oligomeric copolymers (OCPs) are absent from the lubricant compositions according to the present invention.

Oligomeric copolymers are preferably ethylene-propylene copolymers having a number average molecular weight Mn within the range of about 20000 to about 150000 g/mol. Such oligomeric copolymers are for instance described in U.S. Pat. No. 5,451,630. Oligomeric copolymers are typically used in the art as viscosity modifying agents in lubricant compositions with improved shear stability. One preferred oligomeric copolymer is Lubrizol 8407®.

In another preferred embodiment of the present invention, high viscosity esters (complex esters) are absent from the lubricant compositions according to the present invention.

High viscosity esters (complex esters) have been described for instance in WO 2007/144079 A2. High viscosity esters as understood in the context of the present invention have kinematic viscosity according to DIN 51562-1 at 40° C. of at least 400 mm²/s, more preferably at least 600 mm²/s and even more preferably at least 800 mm²/s. This is substantially higher than the viscosity of the esters to be used as essential component in the lubricant compositions according to the present invention.

In another preferred embodiment of the present invention, poly(meth)acrylates (PMAs) are absent from the lubricant compositions according to the present invention.

Poly(meth)acrylates (PMAs) are esters of (meth)acrylic acid that are able to provide improved shear stability in lubricant compositions. Such poly(meth)acrylates are for instance described in DE 3544061. Typical PMAs used in the art are those from the commercial Viscoplex® series of additives. Preferred PMAs are alkylmethacrylate (Viscoplex 0-101), alkylmaleate-alpha-olefin copolymer I (Gear-Lube 7930), alkylfumarate-alpha-olefin-copolymer I (Gear-Lube 7960) and the like.

The ester to be used in the lubricant compositions according to the present invention is included as a solubilizer or co-solvent for the other components assisting in solubilization of polar additives and modifying rheological properties of the lubricant composition.

In its most generic definition as understood in the present invention, the ester component b) is an ester component having kinematic viscosity at 100° C. (DIN 51562-1) in the range of 2 to 15 mm²/s, more preferably 3 to 10 mm²/s and even more preferably 4 to 8 mm²/s.

The ester has a pour point (DIN ISO 3016) in the range of from −20° C. to −75° C., preferably in the range of from −40° C. to −60° C. and most preferably in the range of from −48° C. to −60° C.

The viscosity index (DIN ISO 2909) of the ester is in the range of from 120 to 170, preferably of from 130 to 160, and most preferably of from 135 to 145.

The kinematic viscosity of the ester at 40° C. (DIN 51562-1) is in the range of 7 to 50 mm²/s, preferably 10 to 30 mm²/s and most preferably 12 to 28 mm²/s.

The kinematic viscosity of the ester at 100° C. (DIN 51562-1) is in the range of 2 to 15 mm²/s, preferably 2 to 10 mm²/s, and most preferably 2 to 7 mm²/s.

The ester component b) according to the present invention preferably is a carboxylic acid ester, preferably derived from the reaction of a dicarboxylic acid with an aliphatic alcohol.

Particularly preferred dicarboxylic acids are adipic acid, pimelic acid, suberic acid, azelaic acid and sebacic acid. The ester component b) used in the present invention is preferably formed from such dicarboxylic acids by esterification with medium-size aliphatic alcohols, which can be linear or branched, preferably C₅ to C₂₀ alcohol, more preferably C₁₀ to C₁₅ aliphatic alcohol and most preferably isodecanol, isotridecanol and 2-propyl heptanol.

Another preferred group of alcohols is derived from so-called Guerbet alcohols or mixtures thereof. The trivial name of Guerbet alcohol is used for 2-alkyl-substituted 1-alkanols whose industrial synthesis is described inter alia in H. Machemer, Angewandte Chemie, Vol. 64, pages 213-220 (1952) and in G. Dieckelmann and H. J. Heinz in “The Basics of Industrial Oleochemistry”, pages 145-145 (1988). In one preferred embodiment the Guerbet alcohol is derived at least partly from 2-hexyl decanol, 2-hexyl dodecanol, 2-octyl decanol and/or 2-octyl dodecanol.

Alternatively or additionally, the ester component b) used in the present invention can be a trimethylolpropane-type ester, preferably formed with C₈-C₁₀ aliphatic alcohol and/or an alkylated naphthalene compound having kinematic viscosity at 100° C. (DIN 51562-1) in the range of from 2 to 15 mm²/s. The alkylated naphthalene is an alkyl-substituted naphthalene wherein alkyl is either linear or branched C₁ to C₂₀ alkyl group. There can be a single alkyl substitutent or several alkyl substituents. The preparation of the alkylated naphthalenes is described in US 2008/0300157. However, alternatively or additionally, alkylated naphthalene compounds can be also prepared by the reaction of naphthalene with unsaturated fatty acid esters, preferably with C₈ to C₂₀ unsaturated monocarboxylic acids, most preferably methyloleate, as described in US 2013/0267450 leading to the corresponding ester compound. Preferred alkylated naphthalene compounds to be used in the lubricant compositions according to the present invention include AN Synesstic™ 5 and AN Synesstic™ 12 (Exxon).

Particularly preferred ester components b) are selected from the list consisting of diisodecyl adipate (DIDA), diisotridecyl adipate (DITA), di-propylheptyl adipate (DPHA) and trimethylolpropane caprylate (TMTC). Such esters are for example commercially available under the trademark Synative ES DITA®, Synative ES DIDA® or Synative ES TMTC® (from BASF SE).

The ester component b) is contained in the lubricant compositions according to the present invention in an amount of 5 to 20 wt %, preferably 8 to 15 wt % and most preferably 10 to 12 wt % based on the composition.

The ratio of the highly reactive polyisobutene to the ester component b) in the lubricant compositions according to the present invention is in the range of from 1:12 to 12:1, preferably 1:2 to 12:1, more preferably 1:1 to 6:1, and still more preferably in the range of from 2:1 to 4:1 based on the relative weight of these components in the lubricant compositions according to the present invention.

The lubricant compositions according to the present invention may also comprise an additive component.

The additive component as used in the present invention may include an additive package and/or performance additives.

The additive package as used in the present invention as well as the compounds relating to performance additives are considered mixtures of additives that are typically used in lubricant compositions in limited amounts for mechanically, physically or chemically stabilizing the lubricant compositions while special performance characteristics can be further established by the individual or combined presence of such selected additives.

Additive packages are separately defined in the present invention since a variety of such additive packages are commercially available and typically used in lubricant compositions. One such preferred additive package that is commercially available is marketed under the name Anglamol6004J®.

However, the individual components contained in the additive packages and/or the compounds further defined in the present invention as so-called performance additives include a larger number of different types of additives including dispersants, metal deactivators, detergents, extreme pressure agents (typically boron- and/or sulfur- and/or phosphorus-containing), anti-wear agents, antioxidants (such as hindered phenols, aminic antioxidants or molybdenum compounds), corrosion inhibitors, foam inhibitors, demulsifiers, pour point depressants, seal swelling agents, friction modifiers and mixtures thereof.

The additive component as the sum of all additives contained in the lubricant compositions according to the present invention also including all additives contained in an additive package or added separately is present in the lubricant compositions of the present invention in an amount of 0 to 20 wt %, preferably 0.1 to 15 wt %, more preferably 2 to 12 wt %, and most preferably in an amount of 3 to 10 wt %.

Extreme pressure agents include compounds containing boron and/or sulfur and/or phosphorus. The extreme pressure agent may be present in the lubricant compositions at 0% by weight to 20% by weight, or 0.05% by weight to 10% by weight, or 0.1% by weight to 8% by weight of the lubricant composition.

In one embodiment according to the present invention, the extreme pressure agent is a sulfur-containing compound. In one embodiment, the sulfur-containing compound may be a sulfurised olefin, a polysulfide, or mixtures thereof. Examples of the sulfurised olefin include a sulfurised olefin derived from propylene, isobutylene, pentene; an organic sulfide and/or polysulfide including benzyldisulfide; bis-(chlorobenzyl) disulfide; dibutyl tetrasulfide; di-tertiary butyl polysulfide; and sulfurised methyl ester of oleic acid, a sulfurised alkylphenol, a sulfurised dipentene, a sulfurised terpene, a sulfurised Diels-Alder adduct, an alkyl sulphenyl N′N-dialkyl dithiocarbamates; or mixtures thereof.

In one embodiment the sulfurised olefin includes a sulfurised olefin derived from propylene, isobutylene, pentene or mixtures thereof.

In one embodiment according to the present invention, the extreme pressure agent sulfur-containing compound includes a dimercaptothiadiazole or derivative, or mixtures thereof. Examples of the dimercaptothiadiazole include compounds such as 2,5-dimercapto-1,3,4-thiadiazole or a hydrocarbyl-substituted 2,5-dimercapto-1,3,4-thiadiazole, or oligomers thereof. The oligomers of hydrocarbyl-substituted 2,5-dimercapto-1,3,4-thiadiazole typically form by forming a sulfur-sulfur bond between 2,5-dimercapto-1,3,4-thiadiazole units to form derivatives or oligomers of two or more of said thiadiazole units. Suitable 2,5-dimercapto-1,3,4-thiadiazole derived compounds include for example 2,5-bis(tert-nonyldithio)-1,3,4-thiadiazole or 2-tert-nonyldithio-5-mercapto-1,3,4-thiadiazole. The number of carbon atoms on the hydrocarbyl substituents of the hydrocarbyl-substituted 2,5-dimercapto-1,3,4-thiadiazole typically include 1 to 30, or 2 to 20, or 3 to 16.

In one embodiment, the dimercaptothiadiazole may be a thiadiazole-functionalised dispersant. A detailed description of the thiadiazole-functionalised dispersant is described is paragraphs [0028] to [0052] of International Publication WO 2008/014315.

The thiadiazole-functionalised dispersant may be prepared by a method including heating, reacting or complexing a thiadiazole compound with a dispersant substrate. The thiadiazole compound may be covalently bonded, salted, complexed or otherwise solubilised with a dispersant, or mixtures thereof.

The relative amounts of the dispersant substrate and the thiadiazole used to prepare the thiadiazole-functionalised dispersant may vary. In one embodiment the thiadiazole compound is present at 0.1 to 10 parts by weight relative to 100 parts by weight of the dispersant substrate. In different embodiments the thiadiazole compound is present at greater than 0.1 to 9, or greater than 0.1 to less than 5, or 0.2 to less than 5:to 100 parts by weight of the dispersant substrate. The relative amounts of the thiadiazole compound to the dispersant substrate may also be expressed as (0.1-10):100, or (>0.1-9):100, (such as (>0.5-9):100), or (0.1 to less than 5):100, or (0.2 to less than 5):100.

In one embodiment the dispersant substrate is present at 0.1 to 10 parts by weight relative to 1 part by weight of the thiadiazole compound. In different embodiments the dispersant substrate is present at greater than 0.1 to 9, or greater than 0.1 to less than 5, or about 0.2 to less than 5:to 1 part by weight of the thiadiazole compound. The relative amounts of the dispersant substrate to the thiadiazole compound may also be expressed as (0.1-10):1, or (>0.1-9):1, (such as (>0.5-9):1), or (0.1 to less than 5):1, or (0.2 to less than 5):1.

The thiadiazole-functionalised dispersant may be derived from a substrate that includes a succinimide dispersant (for example, N-substituted long chain alkenyl succinimides, typically a polyisobutylene succinimide), a Mannich dispersant, an ester-containing dispersant, a condensation product of a fatty hydrocarbyl monocarboxylic acylating agent with an amine or ammonia, an alkyl amino phenol dispersant, a hydrocarbyl-amine dispersant, a polyether dispersant, a polyetheramine dispersant, a viscosity modifier containing dispersant functionality (for example polymeric viscosity index modifiers containing dispersant functionality), or mixtures thereof. In one embodiment the dispersant substrate includes a succinimide dispersant, an ester-containing dispersant or a Mannich dispersant.

In one embodiment according to the present invention, the extreme pressure agent includes a boron-containing compound. The boron-containing compound includes a borate ester (which in some embodiments may also be referred to as a borated epoxide), a borated alcohol, a borated dispersant, a borated phospholipid or mixtures thereof. In one embodiment the boron-containing compound may be a borate ester or a borated alcohol.

The borate ester may be prepared by the reaction of a boron compound and at least one compound selected from epoxy compounds, halohydrin compounds, epihalohydrin compounds, alcohols and mixtures thereof. The alcohols include dihydric alcohols, trihydric alcohols or higher alcohols, with the proviso for one embodiment that hydroxyl groups are on adjacent carbon atoms, i.e., vicinal.

Boron compounds suitable for preparing the borate ester include the various forms selected from the group consisting of boric acid (including metaboric acid, orthoboric acid and tetraboric acid), boric oxide, boron trioxide and alkyl borates. The borate ester may also be prepared from boron halides.

In one embodiment suitable borate ester compounds include tripropyl borate, tributyl borate, tripentyl borate, trihexyl borate, triheptyl borate, trioctyl borate, trinonyl borate and tridecyl borate. In one embodiment the borate ester compounds include tributyl borate, tri-2-ethylhexyl borate or mixtures thereof.

In one embodiment, the boron-containing compound is a borated dispersant, typically derived from an N-substituted long chain alkenyl succinimide. In one embodiment the borated dispersant includes a polyisobutylene succinimide. Borated dispersants are described in more detail in U.S. Pat. No. 3,087,936; and U.S. Pat. No. 3,254,025.

In one embodiment the borated dispersant may be used in combination with a sulfur-containing compound or a borate ester.

In one embodiment the extreme pressure agent is other than a borated dispersant.

The number average molecular weight Mn (GPC; g/mol) of the hydrocarbon from which the long chain alkenyl group was derived includes ranges of 350 to 5000 g/mol, or 500 to 3000 g/mol, or 550 to 1500 g/mol. The long chain alkenyl group may have a number average molecular weight Mn of 550 g/mol, or 750 g/mol, or 950 to 1000 g/mol.

The N-substituted long chain alkenyl succinimides are borated using a variety of agents including boric acid (for example, metaboric acid, orthoboric acid and tetraboric acid), boric oxide, boron trioxide, and alkyl borates. In one embodiment the borating agent is boric acid which may be used alone or in combination with other borating agents.

The borated dispersant may be prepared by blending the boron compound and the N-substituted long chain alkenyl succinimides and heating them at a suitable temperature, such as, 80° C. to 250° C., or 90° C. to 230° C., or 100° C. to 210° C., until the desired reaction has occurred. The molar ratio of the boron compounds to the N-substituted long chain alkenyl succinimides may have ranges including 10:1 to 1:4, or 4:1 to 1:3; or the molar ratio of the boron compounds to the N-substituted long chain alkenyl succinimides may be 1:2. Alternatively, the ratio of moles B:moles N (that is, atoms of B:atoms of N) in the borated dispersant may be 0.25:1 to 10:1 or 0.33:1 to 4:1 or 0.2:1 to 1.5:1, or 0.25:1 to 1.3:1 or 0.8:1 to 1.2:1 or about 0.5:1 An inert liquid may be used in performing the reaction. The liquid may include toluene, xylene, chlorobenzene, dimethylformamide or mixtures thereof.

In one embodiment, the additive component in the lubricant composition according to the present invention further includes a borated phospholipid. The borated phospholipid may be derived from boronation of a phospholipid (for example boronation may be carried out with boric acid). Phospholipids and lecithins are described in detail in Encyclopedia of Chemical Technology, Kirk and Othmer, 3rd Edition, in “Fats and Fatty Oils”, Volume 9, pages 795-831 and in “Lecithins”, Volume 14, pages 250-269.

The phospholipid may be any lipid containing a phosphoric acid, such as lecithin or cephalin, or derivatives thereof. Examples of phospholipids include phosphatidylcholine, phosphatidylserine, phosphatidylinositol, phosphatidyl-ethanolamine, phosphotidic acid and mixtures thereof. The phospholipids may be glycerophospholipids, glycerol derivatives of the above list of phospholipids. Typically, the glycerophospholipids have one or two acyl, alkyl or alkenyl groups on a glycerol residue. The alkyl or alkenyl groups may contain 8 to 30, or 8 to 25, or 12 to 24 carbon atoms. Examples of suitable alkyl or alkenyl groups include octyl, dodecyl, hexadecyl, octadecyl, docosanyl, octenyl, dodecenyl, hexadecenyl and octadecenyl.

Phospholipids may be prepared synthetically or derived from natural sources. Synthetic phospholipids may be prepared by methods known to those in the art. Naturally derived phospholipids are often extracted by procedures known to those in the art. Phospholipids may be derived from animal or vegetable sources. A useful phospholipid is derived from sunflower seeds. The phospholipid typically contains 35% to 60% phosphatidylcholine, 20% to 35% phosphatidylinositol, 1% to 25% phosphatidic acid, and 10% to 25% phosphatidylethanolamine, wherein the percentages are by weight based on the total phospholipids. The fatly acid content may be 20% by weight to 30% by weight palmitic acid, 2% by weight to 10% by weight stearic acid, 15% by weight to 25% by weight oleic acid, and 40% by weight to 55% by weight linoleic acid.

In another embodiment, the performance additive in the lubricant compositions according to the present invention may include a friction modifier. A friction modifier is any material or materials that can alter the coefficient of friction of a surface lubricated by any lubricant or fluid containing such material(s). Friction modifiers, also known as friction reducers, or lubricity agents or oiliness agents, and other such agents that change the ability of base oils, formulated lubricant compositions, or functional fluids, to modify the coefficient of friction of a lubricated surface may be effectively used in combination with the base oils or lubricant compositions of the present invention if desired. Friction modifiers may include metal-containing compounds or materials as well as ashless compounds or materials, or mixtures thereof. Metal-containing friction modifiers may include metal salts or metal-ligand complexes where the metals may include alkali, alkaline earth, or transition group metals. Such metal-containing friction modifiers may also have low-ash characteristics. Transition metals may include Mo, Sb, Sn, Fe, Cu, Zn, and others. Ligands may include hydrocarbyl derivative of alcohols, polyols, glycerols, partial ester glycerols, thiols, carboxylates, carbamates, thiocarbamates, dithiocarbamates, phosphates, thiophosphates, dithiophosphates, amides, imides, amines, thiazoles, thiadiazoles, dithiazoles, diazoles, triazoles, and other polar molecular functional groups containing effective amounts of O, N, S, or P, individually or in combination. In particular, Mo-containing compounds can be particularly effective such as for example Mo-dithiocarbamates, Mo(DTC), Mo-dithiophosphates, Mo(DTP), Mo-amines, Mo (Am), Mo-alcoholates, Mo-alcohol-amides, and the like.

Ashless friction modifiers may also include lubricant materials that contain effective amounts of polar groups, for example, hydroxyl-containing hydrocarbyl base oils, glycerides, partial glycerides, glyceride derivatives, and the like. Polar groups in friction modifiers may include hydrocarbyl groups containing effective amounts of O, N, S, or P, individually or in combination. Other friction modifiers that may be particularly effective include, for example, salts (both ash-containing and ashless derivatives) of fatty acids, fatty alcohols, fatty amides, fatty esters, hydroxyl-containing carboxylates, and comparable synthetic long-chain hydrocarbyl acids, alcohols, amides, esters, hydroxy carboxylates, and the like. In some instances fatty organic acids, fatty amines, and sulfurized fatty acids may be used as suitable friction modifiers.

In one embodiment, the performance additive in the lubricant compositions according to the present invention may include phosphorus- or sulfur-containing anti-wear agents other than compounds described as an extreme pressure agent of the amine salt of a phosphoric acid ester described above. Examples of the anti-wear agent may include a non-ionic phosphorus compound (typically compounds having phosphorus atoms with an oxidation state of +3 or +5), a metal dialkyldithiophosphate (typically zinc dialkyldithiophosphates), amine dithiophosphate, ashless dithiophosphates and a metal mono- or di-alkylphosphate (typically zinc phosphates), or mixtures thereof.

The non-ionic phosphorus compound includes a phosphite ester, a phosphate ester, or mixtures thereof.

In one embodiment, the performance additive in the lubricant composition according to the present invention may further include at least one antioxidant. Antioxidants retard the oxidative degradation of base stocks during service. Such degradation may result in deposits on metal surfaces, the presence of sludge, or a viscosity increase in the lubricant. One skilled in the art knows a wide variety of oxidation inhibitors that are useful in lubricating oil compositions.

Useful antioxidants include hindered phenols. These phenolic antioxidants may be ashless (metal-free) phenolic compounds or neutral or basic metal salts of certain phenolic compounds. Typical phenolic antioxidant compounds are the hindered phenolics which are the ones which contain a sterically hindered hydroxyl group, and these include those derivatives of dihydroxy aryl compounds in which the hydroxyl groups are in the o- or p-position to each other. Typical phenolic antioxidants include the hindered phenols substituted with C₆₊ alkyl groups and the alkylene coupled derivatives of these hindered phenols. Examples of phenolic materials of this type 2-t-butyl-4-heptyl phenol; 2-t-butyl-4-octyl phenol; 2-t-butyl-4-dodecyl phenol; 2,6-di-t-butyl-4-heptyl phenol; 2,6-di-t-butyl-4-dodecyl phenol; 2-methyl-6-t-butyl-4-heptyl phenol; and 2-methyl-6-t-butyl-4-dodecyl phenol. Other useful hindered mono-phenolic antioxidants may include for example hindered 2,6-di-alkyl-phenolic propionic ester derivatives. Bis-phenolic antioxidants may also be advantageously used in combination with the instant invention. Examples of ortho-coupled phenols include: 2,2′-bis(4-heptyl-6-t-butyl-phenol); 2,2′-bis(4-octyl-6-t-butyl-phenol); and 2,2′-bis(4-dodecyl-6-t-butyl-phenol). Para-coupled bisphenols include for example 4,4′-bis(2,6-di-t-butyl phenol) and 4,4′-methylene-bis(2,6-di-t-butyl phenol).

Non-phenolic oxidation inhibitors which may be used include aromatic amine antioxidants and these may be used either as such or in combination with phenolics. Typical examples of non-phenolic antioxidants include: alkylated and non-alkylated aromatic amines such as aromatic monoamines of the formula R⁸R⁹R¹⁰N, where R⁸ is an aliphatic, aromatic or substituted aromatic group, R⁹ is an aromatic or a substituted aromatic group, and R¹⁰ is H, alkyl, aryl or R¹¹S(O)_(x)R¹², where R¹¹ is an alkylene, alkenylene, or aralkylene group, R¹² is a higher alkyl group, or an alkenyl, aryl, or alkaryl group, and x is 0, 1 or 2. The aliphatic group R⁸ may contain from 1 to about 20 carbon atoms, and preferably contains from about 6 to 12 carbon atoms. The aliphatic group is a saturated aliphatic group. Preferably, both R⁸ and R⁹ are aromatic or substituted aromatic groups, and the aromatic group may be a fused ring aromatic group such as naphthyl. Aromatic groups R⁸ and R⁹ may be joined together with other groups such as S.

Typical aromatic amines antioxidants have alkyl substituent groups of at least about 6 carbon atoms. Examples of aliphatic groups include hexyl, heptyl, octyl, nonyl, and decyl. Generally, the aliphatic groups will not contain more than about 14 carbon atoms. The general types of amine antioxidants useful in the present compositions include diphenylamines, phenyl naphthylamines, phenothiazines, imidodibenzyls and diphenyl phenylene diamines. Mixtures of two or more aromatic amines are also useful. Polymeric amine antioxidants can also be used. Particular examples of aromatic amine antioxidants useful in the present invention include: p,p′-dioctyldiphenylamine; t-octylphenyl-alpha-naphthylamine; phenyl-alphanaphthylamine; and p-octylphenyl-alpha-naphthylamine. Sulfurized alkyl phenols and alkali or alkaline earth metal salts thereof also are useful antioxidants.

In one embodiment, the performance additive in the lubricant compositions according to the present invention further includes a dispersant. The dispersant may be a succinimide dispersant (for example N-substituted long chain alkenyl succinimides), a Mannich dispersant, an ester-containing dispersant, a condensation product of a fatty hydrocarbyl monocarboxylic acylating agent with an amine or ammonia, an alkyl amino phenol dispersant, a hydrocarbylamine dispersant, a polyether dispersant or a polyetheramine dispersant.

In one embodiment the succinimide dispersant includes a polyisobutylene-substituted succinimide, wherein the polyisobutylene from which the dispersant is derived may have a number average molecular weight of 400 to 5000 g/mol, or 950 to 1600 g/mol. Succinimide dispersants and their methods of preparation are more fully described in U.S. Pat. Nos. 4,234,435 and 3,172,892. Suitable ester-containing dispersants are typically high molecular weight esters. These materials are described in more detail in U.S. Pat. No. 3,381,022.

In one embodiment the dispersant includes a borated dispersant. Typically the borated dispersant includes a succinimide dispersant including a polyisobutylene succinimide, wherein the polyisobutylene from which the dispersant is derived may have a number average molecular weight of 400 to 5000 g/mol. Borated dispersants are described in more detail above within the extreme pressure agent description.

Dispersant viscosity modifiers (often referred to as DVMs) are considered additives in the context of the present invention due to their additional functionalisation and are therefore not considered viscosity improving agents according to the present invention. Dispersant viscosity modifiers include functionalised polyolefins, for example, ethylene-propylene copolymers that have been functionalized with the reaction product of maleic anhydride and an amine, a polymethacrylate functionalised with an amine, or esterified styrene-maleic anhydride copolymers reacted with an amine.

As another type of performance additives, corrosion inhibitors can be described as any materials (additives, functionalized fluids, etc.) that form a protective film on a surface that prevents corrosion agents from reacting or attacking that surface with a resulting loss of surface material. Protective films may be absorbed on the surface or chemically bonded to the surface. Protective films may be constituted from mono-molecular species, oligomeric species, polymeric species, or mixtures thereof. Protective films may derive from the intact corrosion inhibitors, from their combination products, or their degradation products, or mixtures thereof. Surfaces that may benefit from the action of corrosion inhibitors may include metals and their alloys (both ferrous and non-ferrous types) and non-metals.

Corrosion inhibitors may include various oxygen-, nitrogen-, sulfur-, and phosphorus-containing materials, and may include metal-containing compounds (salts, organometallics, etc.) and nonmetal-containing or ashless materials. Corrosion inhibitors may include, but are not limited to, additive types such as, for example, hydrocarbyl-, aryl-, alkyl-, arylalkyl-, and alkylaryl-versions of detergents (neutral, overbased), sulfonates, phenates, salicylates, alcoholates, carboxylates, salixarates, phosphites, phosphates, thiophosphates, amines, amine salts, amine phosphoric acid salts, amine sulfonic acid salts, alkoxylated amines, etheramines, polyetheramines, amides, imides, azoles, diazoles, triazoles, benzotriazoles, benzothiadoles, mercaptobenzothiazoles, tolyltriazoles (TTZ-type), heterocyclic amines, heterocyclic sulfides, thiazoles, thiadiazoles, mercaptothiadiazoles, dimercaptothiadiazoles (DMTD-type), imidazoles, benzimidazoles, dithiobenzimidazoles, imidazolines, oxazolines, Mannich reactions products, glycidyl ethers, anhydrides, carbamates, thiocarbamates, dithiocarbamates, polyglycols, etc., or mixtures thereof.

Corrosion inhibitors are used to reduce the degradation of metallic parts that are in contact with the lubricant composition. Suitable corrosion inhibitors include thiadiazoles. Aromatic triazoles, such as tolyltriazole, are suitable corrosion inhibitors for non-ferrous metals, such as copper.

Metal deactivators include derivatives of benzotriazoles (typically tolyltriazole), 1,2,4-triazoles, benzimidazoles, 2-alkyldithiobenzimidazoles, thiadiazoles or 2-alkyldithiobenzothiazoles.

Foam inhibitors may also advantageously be added as a performance additive to the lubricant compositions according to the present invention. These agents retard the formation of stable foams. Silicones and organic polymers are typical foam inhibitors. For example, polysiloxanes, such as silicon oil, or polydimethylsiloxane, provide foam inhibiting properties. Further foam inhibitors include copolymers of ethyl acrylate and 2-ethylhexyl acrylate and optionally vinyl acetate.

Demulsifiers include trialkyl phosphates, and various polymers and copolymers of ethylene glycol, ethylene oxide, propylene oxide, or mixtures thereof.

As pour point depressants, esters of maleic anhydride-styrene, or polyacrylamides are included.

As a further performance additive to be used in the lubricant compositions according to the present invention, seal compatibility agents help to swell elastomeric seals by causing a chemical reaction in the fluid or physical change in the elastomer. Suitable seal compatibility agents for lubricant compositions include organic phosphates, aromatic esters, aromatic hydrocarbons, esters (butylbenzyl phthalate, for example), and polybutenyl succinic anhydride. Such additives may preferably be used in an amount of 0.01 to 3% by weight, more preferably 0.01 to 2% by weight of the total amount of the lubricant composition.

The base oil to be used in the lubricant compositions according to the present invention is an optional component but is nonetheless preferably present in the lubricant compositions.

The base oil (or base stock) to be used in the lubricant compositions according to the present invention is an inert, solvent-type oil component in the lubricant compositions according to the present invention.

Preferably, the lubricant compositions according to the present invention further comprise base oils selected from the group consisting of mineral oils (Group I, II or III oils), polyalphaolefins (Group IV oils), polymerized and interpolymerized olefins, alkyl naphthalenes, alkylene oxide polymers, silicone oils, phosphate esters and carboxylic acid esters (Group V oils).

Definitions for the base oils according to the present invention are the same as those found in the American Petroleum Institute (API) publication “Engine Oil Licensing and Certification System”, Industry Services Department, Fourteenth Edition, December 1996, Addendum 1, December 1998. Said publication categorizes base stocks as follows:

a) Group I base oils contain less than 90 percent saturates and/or greater than 0.03 percent sulfur and have a viscosity index greater than or equal to 80 and less than 120 using the test methods specified in the following table.

b) Group II base oils contain greater than or equal to 90 percent saturates and less than or equal to 0.03 percent sulfur and have a viscosity index greater than or equal to 80 and less than 120 using the test methods specified in the following table.

c) Group III base oils contain greater than or equal to 90 percent saturates and less than or equal to 0.03 percent sulfur and have a viscosity index greater than or equal to 120 using the test methods specified in the following table

Analytical Methods for Base Stock:

Property Test Method Saturates ASTM D 2007 Viscosity Index ASTM D 2270 Sulfur ASTM D 2622 ASTM D 4294 ASTM D 4927 ASTM D 3120

d) Group IV base oils contain polyalphaolefins. Synthetic lower viscosity fluids suitable for the present invention include the polyalphaolefins (PAOs) and the synthetic oils from the hydro-cracking or hydro-isomerization of Fischer Tropsch high boiling fractions including waxes. These are both base oils comprised of saturates with low impurity levels consistent with their synthetic origin. The hydro-isomerized Fischer Tropsch waxes are highly suitable base oils, comprising saturated components of iso-paraffinic character (resulting from the isomerization of the predominantly n-paraffins of the Fischer Tropsch waxes) which give a good blend of high viscosity index and low pour point. Processes for the hydro-isomerization of Fischer Tropsch waxes are described in U.S. Pat. Nos. 5,362,378; 5,565,086; 5,246,566 and 5,135,638, as well in EP 710710, EP 321302 and EP 321304.

Polyalphaolefins suitable for the lubricant compositions according to the present invention, include known PAO materials which typically comprise relatively low molecular weight hydrogenated polymers or oligomers of alphaolefins which include but are not limited to C₂ to about C₃₂ alphaolefins with the C₈ to about C₁₆ alphaolefins, such as 1-octene, 1-decene, 1-dodecene and the like being preferred. The preferred polyalphaolefins are poly-1-octene, poly-1-decene, and poly-1-dodecene, although the dimers of higher olefins in the range of C₁₄ to C₁₈ provide low viscosity base stocks.

Terms like PAO 4, PAO 6 or PAO 8 are commonly used specifications for different classes of polyalphaolefins characterized by their respective viscosity. For instance, PAO 6 refers to the class of polyalphaolefins which typically has viscosity in the range of 6 mm²/s at 100° C. A variety of commercially available compositions are available for these specifications.

Low viscosity PAO fluids suitable for the lubricant compositions according to the present invention, may be conveniently made by the polymerization of an alphaolefin in the presence of a polymerization catalyst such as the Friedel-Crafts catalysts including, for example, aluminum trichloride, boron trifluoride or complexes of boron trifluoride with water, alcohols such as ethanol, propanol or butanol, carboxylic acids or esters such as ethyl acetate or ethyl propionate. For example, the methods disclosed by U.S. Pat. Nos. 3,149,178 or 3,382,291 may be conveniently used herein. Other descriptions of PAO synthesis are found in the following U.S. patents: U.S. Pat. No. 3,742,082 (Brennan); U.S. Pat. No. 3,769,363 (Brennan); U.S. Pat. No. 3,876,720 (Heilman); U.S. Pat. No. 4,239,930 (Allphin); U.S. Pat. No. 4,367,352 (Watts); U.S. Pat. No. 4,413,156 (Watts); U.S. Pat. No. 4,434,308 (Larkin); U.S. Pat. No. 4,910,355 (Shubkin); U.S. Pat. No. 4,956,122 (Watts); and U.S. Pat. No. 5,068,487 (Theriot).

e) Group V base oils contain any base stocks not described by Groups I to IV. Examples of Group V base oils include alkyl naphthalenes, alkylene oxide polymers, silicone oils, and phosphate esters.

Carboxylic acid esters which are also widely considered in the literature to belong to the Group V base oils are not understood according to the present invention as base oils (base stocks) or even group V base oils but are separately listed as the ester component being essential to the present invention.

Synthetic base oils include hydrocarbon oils and halo-substituted hydrocarbon oils such as polymerized and interpolymerized olefins (e.g., polypropylenes, propylene-isobutylene copolymers, chlorinated polybutylenes, poly(1-hexenes), poly(1-octenes), poly(1-decenes)); alkylbenzenes (e.g., dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes, di(2-ethylhexyl)benzenes); polyphenyls (e.g., biphenyls, terphenyls, alkylated polyphenols); and alkylated diphenyl ethers and alkylated diphenyl sulfides and derivative, analogs and homologs thereof.

Alkylene oxide polymers and interpolymers and derivatives thereof where the terminal hydroxyl groups have been modified by esterification, etherification, etc., constitute another class of known synthetic base oils. These are exemplified by polyoxyalkylene polymers prepared by polymerization of ethylene oxide or propylene oxide, and the alkyl and aryl ethers of polyoxyalkylene polymers (e.g., methyl-polyiso-propylene glycol ether having a molecular weight of 1000 g/mol or diphenyl ether of polyethylene glycol having a molecular weight of 1000 to 1500 g/mol); and mono- and polycarboxylic esters thereof, for example, the acetic acid esters, mixed C₃-C₈ fatty acid esters and C₁₃ Oxo acid diester of tetraethylene glycol.

Silicon-based oils such as the polyalkyl-, polyaryl-, polyalkoxy- or polyaryloxysilicone oils and silicate oils comprise another useful class of synthetic base oils; such base oils include tetraethyl silicate, tetraisopropyl silicate, tetra-(2-ethylhexyl)silicate, tetra-(4-methyl-2-ethylhexyl)silicate, tetra-(p-tert-butyl-phenyl) silicate, hexa-(4-methyl-2-ethylhexyl)disiloxane, poly(methyl)siloxanes and poly(methylphenyl)siloxanes. Other synthetic base oils include liquid esters of phosphorus-containing acids (e.g., tricresyl phosphate, trioctyl phosphate, diethyl ester of decylphosphonic acid) and polymeric tetrahydrofurans.

The relative amount of base oil in the lubricant compositions according to the present invention is in the range of 0 to 80 wt %, preferably 20 to 35 or 45 to 70 wt %, or more preferably in the range of 50 to 60 wt % based on the total amount of lubricant composition.

The present invention provides lubricant compositions which have excellent low temperature viscosity, particularly low dynamic low temperature viscosity. For instance, it is preferred that the lubricant composition according to the present invention have kinematic viscosity at −40° C. according to DIN 51562-1, of not higher than 110000 mm²/s, preferably not higher than 105000 mm²/s, and most preferably below 100000 mm²/s, or preferably in the range of from 50000 to 110000 mm²/s, or even more preferably in the range of from 70000 to 100000 mm²/s.

Additionally or alternatively, the favorable properties are also indicated by the very low pour points of the lubricant compositions according to the present invention and only very limited loss of viscosity after shear as measured by the test according to DIN 51350-06/KRL/C. The lubricant combinations according to the present invention therefore provide superior performance characteristics when compared to the state-of-the-art lubricants that are commercially available, e.g. Emgard UAF 4209® of BASF SE. The lubricant compositions according to the present invention also have very good oxidation stability. This is surprising considering the high number of terminal double bonds in the highly reactive polyisobutenes which would have rather pointed to inferior stability and unfavorable mechanical performance characteristics, particularly in terms of oxidation stability.

The lubricant compositions according to the present invention further provide very attractive cost profiles when compared to the presently marketed lubricant formulations since it has been demonstrated by the present invention that relatively expensive thickening components can be partially or even completely replaced by the less costly highly reactive polyisobutenes while at least comparable performance characteristics can still be achieved.

For instance, the conventional polyisobutenes, e.g. the commercial product Lubrizol 8406®, typically contained as thickening component in common lubricant compositions could be completely replaced by highly reactive polyisobutenes, e.g. Glissopal V1500®, to yield lubricant compositions with even lower pour points while other important properties oxidation stability could be maintained (see Test Example 1).

Preferred lubricant compositions according to the present invention are as follows: As a lubricant composition which is free of base-oil, the following lubricant composition is preferred.

base-oil-free lubricant highly-reactive polyisobutene 75-90 wt % (30-45 mm²/s [100° C.], Mn 500 to 700 g/mol, GPC) ester  7-15 wt % additive component  3-10 wt %

Such a preferred base oil-free lubricant composition according to the present invention as defined above comprises a highly-reactive polyisobutene, a low viscosity ester and an additive package as components wherein other viscosity index improving agents as mentioned above are preferably not used in addition to the highly-reactive polyisobutene component.

The lubricant composition IE-2 as depicted in the Test Examples below is considered such a preferred base oil-free lubricant composition according to the present invention. Another preferred lubricant composition according to the present invention is defined as follows:

base-oil-containing lubricant highly-reactive polyisobutene 25-35 wt % (160-220 mm²/s [100° C.], Mn 800 to 1200 g/mol, GPC) ester  7-13 wt % additive component  2-6 wt % base oil 50-65 wt %

Such a preferred base oil-containing lubricant composition according to the present invention as defined above comprises a highly-reactive polyisobutene, a low viscosity ester and an additive package in combination with a base oil as components wherein other viscosity index improving agents as mentioned above are preferably not used in addition to the highly-reactive polyisobutene component.

The lubricant composition IE-3 as depicted in the Test Examples below is considered such a preferred base oil-containing lubricant composition according to the present invention.

Another preferred lubricant composition according to the present invention is defined as follows:

base-oil-containing lubricant highly-reactive polyisobutene  15-30 wt % (1200-1600 mm²/s [100° C.], Mn 2000 to 2500 g/mol, GPC) ester   7-13 wt % additive component   2-6 wt % base oil  45-60 wt % antioxidant  0.5-2 wt %

Such a preferred base oil-containing lubricant composition according to the present invention as defined above comprises a highly-reactive polyisobutene, an ester, an additive component and an essential antioxidant component in combination with a base oil as essential component wherein other viscosity index improving agents as mentioned above are preferably not used in addition to the highly-reactive polyisobutene component.

The lubricant composition IE-5 as depicted in the Examples below is considered such a preferred base oil-containing lubricant composition according to the present invention.

Another preferred lubricant composition according to the present invention is defined as follows:

base-oil-containing lubricant with additional viscosity index-improving agent highly-reactive polyisobutene  10-14 wt % (1200-1600 mm²/s [100° C.], Mn 2000 to 2500 g/mol, GPC) additional viscosity index improving agent  10-14 wt % ester   7-13 wt % additive component  10-14 wt % base oil  45-55 wt % antioxidant  0.5-2 wt %

Such a preferred base oil-containing lubricant composition according to the present invention as defined above comprises a highly-reactive polyisobutene in combination with a further viscosity index-improving agent which does however not include a conventional polyisobutene component (like the conventional polyisobutene Lubrizol 8406®) as viscosity index-improving agent but rather an additional alternative viscosity index improving agent like an oligomeric copolymer (OCP), a polymethylacrylate (PMA), a complex (high viscosity) ester or the like. Further, an ester, an additive component and an antioxidant component in combination with base oil are used as the additional essential components of this preferred lubricant composition according to the present invention.

The lubricant composition IE-1 as depicted in the Examples below is considered such a preferred base oil-containing lubricant composition according to the present invention.

The lubricant compositions according to the present invention can be used in a variety of different applications. Preferred embodiments include the use of the lubricant compositions according to the present invention in light, medium and heavy duty engine oils, industrial engine oils, marine engine oils, automotive engine oils, crankshaft oils, compressor oils, refrigerator oils, hydrocarbon compressor oils, very low-temperature lubricating oils and fats, high temperature lubricating oils and fats, wire rope lubricants, textile machine oils, refrigerator oils, aviation and aerospace lubricants, aviation turbine oils, transmission oils, gas turbine oils, spindle oils, spin oils, traction fluids, transmission oils, plastic transmission oils, passenger car transmission oils, truck transmission oils, industrial transmission oils, industrial gear oils, insulating oils, instrument oils, brake fluids, transmission liquids, shock absorber oils, heat distribution medium oils, transformer oils, fats, chain oils, minimum quantity lubricants for metalworking operations, oil to the warm and cold working, oil for water-based metalworking liquids, oil for neat oil metalworking fluids, oil for semi-synthetic metalworking fluids, oil for synthetic metalworking fluids, drilling detergents for the soil exploration, hydraulic oils, in biodegradable lubricants or lubricating greases or waxes, chain saw oils, release agents, moulding fluids, gun, pistol and rifle lubricants or watch lubricants and food grade approved lubricants.

EXAMPLES

Methods

The terminal double bonds in the highly reactive polyisobutene polymers are defined in the present invention as the double bonds according to the following formula wherein R means the polyisobutene radical.

The amount of terminal double bonds in the highly reactive polyisobutenes is determined following the method mentioned in U.S. Pat. No. 5,962,604 using ¹³C-NMR spectroscopy based on the relative peak areas corresponding to the signals for the C-alpha and C-beta carbon atom (chemical shift of 114.4 ppm and 143.6 ppm), respectively.

Measurement of the number average molecular weight of polymers mentioned in the present invention has been carried out using the industrial standard DIN 55672.

The pour point of the lubricant compositions according to the present invention has been determined according to the established industrial standard DIN ISO 3016.

The various viscosities of the lubricant compositions according to the present invention have been determined following established industry standards:

The kinematic viscosity at 40° C. and 100° C., respectively, is determined according to the established industrial standard DIN 51562-1.

Experimental Tests

Test Example 1

Lubricant Inventive examples composition CE-1 IE-1 IE-2 PAO 6 Durasyn 146 Durasyn 146 — 48.6 wt % 48.2 wt % Ester Synative ES Synative ES Synative ES component DIDA DIDA TMTC  8.0 wt %  8.0 wt %  8.0 wt % Additive Anglamol 6004J Anglamol 6004J Anglamol 6004J component 14.0 wt % 14.0 wt %  3.1 wt % OCP I Lubrizol 8407 Lubrizol 8407 — 16.7 wt % 17.0 wt % PMA — — — PIB Lubrizol 8406 — — 12.7 wt % HR-PIB — Glissopal V1500 Glissopal V 33 12.8 wt % 88.94 wt % Pour point −48° C. −57° C. −54° C. Durasyn 146 ® is a mixture of polyalphaolefins produced from C12 linear alphaolefin feed stocks having kinematic viscosity of 5.9 mm²/s at 100° C. (ISO 3104/ASTM D445); Synative ES DIDA ® (Cognis) is a commercially available diisodecyladipate, a low viscosity ester, having kinematic viscosity of 3.69 mm²/s at 100° C. (ASTM D445); the pour point is −48° C. (ASTM D97), the viscosity index has a value of 160 (ASTM D2270); Synative ES TMTC ® (Cognis) is a commercially available trimethylolpropane C8/C10 ester, a low viscosity ester, having kinematic viscosity of 4.3 mm²/s at 100° C. (DIN 51562-1); the pour point is −55° C. (DIN ISO 3016), the viscosity index has a value of 143 (DIN ISO 2909); Anglamol 6004J ® (Lubrizol) is a commercially available additive package; Lubrizol 8407 ® (Lubrizol) is a oligomeric ethylene/propylene copolymer; Lubrizol 8406 ® (Lubrizol) is a conventional polyisobutene; Glissopal V1500 ® (BASF SE) is a highly reactive polyisobutene having a kinematic viscosity of 1500 mm²/s at 100° C. (DIN 51562-1), Mn of 2300 g/mol (GPC); Glissopal V33 ® (BASF SE) is a highly reactive polyisobutene having a kinematic viscosity of 33 mm²/s at 100° C. (DIN 51562-1).

As derivable from the above tests, replacement of the conventional polyisobutene thickener (PIB) by highly reactive polyisobutene polymers (HR-PIB) in conventional lubricant compositions leads to a lubricant composition in which the combination of the low viscosity ester and the highly reactive polyisobutene polymer as thickener component leads to lubricant compositions having exceptionally low pour point.

Lubricant Comparative example Inventive Example composition CE-2 IE-3 PAO 6 36.94 wt % 31.64 wt % Ester — Synative ES DIDA component  8.0 wt % Additive Hitec 307 (Afton) Hitec 307 (Afton) component  5.06 wt %  5.06 wt % OCP I — — PMA Viscobase 11-520 —  58.0 wt % PIB — — HR-PIB — Glissopal V 190  55.3 wt % Viscosity increase 6.50% 5.10% at 100° C. in %; ASTM D 2893 A Hitec 307 ® (Afton) is an industrial gear oil additive package having kinematic viscosity of 13 mm²/s at 100° C.; Glissopal V190 ® (BASF SE) is a highly reactive polyisobutene having a kinematic viscosity of 190 mm²/s at 100° C. (DIN 51562-1) and Mn of 1000 g/mol (GPC); Viscobase 11-520 (Evonik) is a highly concentrated polyalkyl methacrylate in group III oil having kinematic viscosity of 275 mm²/s at 100° C. (ASTM D445);

This oxidation test (industrial standard ASTM D 2893 A) of comparative composition CE-2 with inventive lubricant composition IE-3 revealed superior oxidation stability for inventive composition IE-3 (viscosity increase at 100° C. in %): 

1.-13. (canceled)
 14. A lubricant composition comprising a) 9.0 to 94.0 wt % based on the total amount of lubricant composition of a polyisobutene polymer having a number average molecular weight of 300-5000 g/mol according to DIN 55672 and at least 60 mol % terminal double bonds based on the total number of double bonds in the polymer, and b) 5 to 50 wt % based on the total amount of lubricant composition of an ester component having kinematic viscosity according to DIN 51562-1 in the range of 2 to 15 mm²/s at 100° C., wherein the ratio of the polyisobutene polymer a) to the ester component b) is from 1:12 to 12:1 based on the relative weight of these components in the lubricant composition.
 15. The lubricant composition according to claim 14, further comprising 20 to 80 wt % of a base oil component.
 16. The lubricant composition according to claim 15, wherein the base oil component comprises a polyalphaolefin and/or a Group II and/or Group III mineral oil.
 17. The lubricant composition according to claim 16, wherein the base oil component comprises a polyalphaolefin 4, polyalphaolefin 6 and/or polyalphaolefin
 8. 18. The lubricant composition according to claim 17, wherein the base oil component comprises a polyalphaolefin
 6. 19. The lubricant composition according to claim 14, wherein the composition does not include an ethylene/propylene copolymer.
 20. The lubricant composition according to claim 14, wherein the composition does not include a polyisobutene polymer having less than 60 mol % terminal double bonds.
 21. The lubricant composition according to claim 14, wherein the composition does not include a polyalkylmethacrylate.
 22. The lubricant composition according to claim 14, wherein the ester component is selected from the group consisting of diisodecyladipate, diisotridecyladipate, di(2-propylheptyl)adipate and trimethylolpropanolcaprylate.
 23. The lubricant composition according to claim 14, further comprising an additive component selected from the group consisting of antioxidants, dispersants, foam inhibitors, demulsifiers, seal swelling agents, friction reducers, anti-wear agents, detergents, corrosion inhibitors, extreme pressure agents, metal deactivators, rust inhibitors, pour point depressants and mixtures thereof.
 24. The lubricant composition according to claim 23, wherein the additive component is present in an amount of 0.1 to 20 wt % of the total lubricant composition.
 25. The lubricant composition according to claim 14, having kinematic viscosity at −40° C. according to DIN 51562-1 of not higher than 110000 mm²/s.
 26. A light duty engine oil, medium duty engine oil, heavy duty engine oil, industrial engine oils, marine engine oils, automotive engine oils, crankshaft oils, compressor oils, refrigerator oils, hydrocarbon compressor oils, very low-temperature lubricating oils and fats, high temperature lubricating oils and fats, wire rope lubricants, textile machine oils, refrigerator oils, aviation and aerospace lubricants, aviation turbine oils, transmission oils, gas turbine oils, spindle oils, spin oils, traction fluids, transmission oils, plastic transmission oils, passenger car transmission oils, truck transmission oils, industrial transmission oils, industrial gear oils, insulating oils, instrument oils, brake fluids, transmission liquids, shock absorber oils, heat distribution medium oils, transformer oils, fats, chain oils, minimum quantity lubricants for metalworking operations, oil to the warm and cold working, oil for water-based metalworking liquids, oil for neat oil metalworking fluids, oil for semi-synthetic metalworking fluids, oil for synthetic metalworking fluids, drilling detergents for the soil exploration, hydraulic oils, in biodegradable lubricants or lubricating greases or waxes, chain saw oils, release agents, moulding fluids, gun, pistol and rifle lubricants or watch lubricants and food grade approved lubricants which the comprises the lubricant composition of claim
 14. 